Room-temperature curable compositions comprising an organic polymer having a silicon-containing group which has a hydroxyl or hydrolyzable group bonded to the silicon atom and which is crosslinkable by forming a siloxane bond (hereinafter referred to as a “reactive silicon group”) in combination with an epoxy resin show various properties such as proper workability and curability, stable rubber elasticity over a wide temperature range, good adhesiveness with an adherend, and are widely used as sealing material, coating material, adhesive material, and the like for building use, civil engineering use, industrial use, and the like where epoxy resin or polyurethane resin had been conventionally employed (See Patent document 1, for example).
Reactive silicon group-containing polyoxyalkylene polymers are hydrolyzed and condensed in the presence of a curing catalyst due to moisture in the air, and changes into rubber-like elastomer. However, a curable composition containing said polymer was disadvantageous in that the inside of the composition did not cure over a prolonged period of time in the construction between non-porous substrates though which water was hard to penetrate, the construction where the composition was given thick, the construction under cold and low-humidity conditions during winter season, and the like.
For solving such a problem, proposed is addition of water to the composition (See Patent documents 2 and 3, for example). Both documents disclose the two-component composition which is composed of component A comprising a reactive silicon group-containing polyoxyalkylene polymer, a curing agent for epoxy resin, and a curing catalyst, and component B comprising an epoxy resin and water, and confirm that such constitution improves internal curability of the composition. In this component A, however, the reactive silicon group-containing polyoxyalkylene polymer coexists with its curing catalyst, so that it was disadvantageous in that the air must be strictly cut off during the container-filling upon preparation of component A, its prolonged storage, the mixing procedure with component B, and the like thereby hindering easy handling.
Further, a two-component composition is proposed which employs a specific curing catalyst and thus omits water content control in component A, and which is excellent in internal curability and easy handleability of component A (See Patent document 4, for example). This two-component composition is composed of component A comprising a reactive silicon group-containing polyoxyalkylene polymer, a curing agent for epoxy resin, and a silane coupling agent, and component B comprising an epoxy resin, the specific curing catalyst and water.
Also proposed is a two-component composition which is composed of component A comprising a reactive silicon group-containing polyoxyalkylene polymer, a curing agent for epoxy resin, a silane coupling agent, and water, and component B comprising an epoxy resin, and a curing catalyst, and which can assure the balance between easy handleability of component A and internal curability (See Patent document 5, for example).    Patent document 1: JP 1,727,750, B    Patent document 2: JP Sho63-273,625, A    Patent document 3: JP Hei9-279,047, A    Patent document 4: JP 2002-309,077, A    Patent document 5: JP 2004-225,020, A